1. Field of the Invention
This invention relates, in general, to heat exchangers.
2. Description of the Prior Art
Heat exchangers have long been used to exchange or transfer heat from one fluid to another so as to cause heating or cooling of one of the fluids. Such heat exchangers find wide spread use in coolers, air conditioners, water heaters, etc.
Such heat exchangers operate on the principle of heat transfer through the wall of a conduit from a higher temperature fluid flowing on one side of the conduit wall to a lower temperature fluid flowing on the other side of the conduit wall wherein the higher temperature fluid gives up a portion of its heat to the lower temperature fluid as it flows along the conduit wall. As it is known that heat transfer capability can be increased by exposing a larger heat transfer surface to the flow of the high and low temperature fluids and, also, by utilizing small cross sectional areas of fluid flow which is directly exposed to the heat transfer surface, heat exchangers having concentric tubes or conduits have been developed. In such a heat exchanger, one fluid flows through the inner conduit, with the other fluid flowing through the annular space between the inner and outer conduits, preferably in a counter direction to the first fluid. One or more of such concentrically disposed tube pairs are employed, depending upon the required capacity of the heat exchanger.
It has also been known to incorporate various manifolds and ports within a heat exchanger in order to direct the inner tube fluid flow out of the inner tube and back over a portion of the outer tube to increase the amount of heat transfer surface between the fluids. However, such previously devised heat exchangers offer less than maximum heat transfer capability which detracts from their advantageous use and requires a larger size or capacity heat exchanger in order to obtain a given heat transfer rate.
A major factor in the low efficiency of such previously devised heat exchangers is the occurrence of laminar flow at the heat transfer surface which results in the buildup of a stagnant film barrier. In order to prevent the occurrence of the stagnant film barrier within a heat exchanger, previously devised heat exchangers utilize a variety of turbulence inducing means in order to create turbulent flow of the fluids within the heat exchanger. Such means obviously increase the cost of the heat exchanger and have, to date, done little to improve overall efficiency of such heat exchangers.
Thus, it would be desirable to provide a heat exchanger which overcomes the problems of previously devised heat exchangers relating to less than maximum heat transfer rates. It would also be desirable to provide a heat exchanger which is constructed with relatively inexpensive, readily available components for a low manufacturing cost. It would also be desirable to provide a heat exchanger which can be easily constructed in a variety of sizes. Finally, it would be desirable to provide a heat exchanger which can be used for a variety of applications and for either heating or cooling.